Drip Irrigation Apparatus

ABSTRACT

Drip irrigation apparatus including a main water flow channel having associated therewith along a length thereof a plurality of pressure-controlled drip irrigation emitter units and at least one secondary water flow channel extending generally parallel to the main water flow channel and receiving water from at least one of the plurality of pressure-controlled drip irrigation emitter units, the at least one secondary water flow channel having water outlets disposed along the length of the main water flow channel, intermediate the plurality of pressure-controlled drip irrigation emitter units.

REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. Provisional PatentApplication Ser. No. 60/732,611, filed Nov. 1, 2005 and entitled DRIPIRRIGATION APPARATUS, the disclosure of which is hereby incorporated byreference and priority of which is hereby claimed pursuant to 37 CFR1.78(a) (4) and (5)(i).

FIELD OF THE INVENTION

The present invention relates to drip irrigation apparatus and methodsof manufacture thereof.

BACKGROUND OF THE INVENTION

The following patent publications are believed to represent the currentstate of the art:

U.S. Pat. Nos. 4,177,946; 4,285,472; 4,430,020; 4,473,191; 4,534,515;4,874,132; 5,106,021; 5,615,838; 6,027,048; 6,206,305 and 6,382,530.

SUMMARY OF THE INVENTION

The present invention seeks to provide improved drip irrigationapparatus and methods of manufacture thereof.

There is thus provided in accordance with a preferred embodiment of thepresent invention drip irrigation apparatus including a main water flowchannel having associated therewith along a length thereof a pluralityof pressure-controlled drip irrigation emitter units and at least onesecondary water flow channel extending generally parallel to the mainwater flow channel and receiving water from at least one of theplurality of pressure-controlled drip irrigation emitter units, the atleast one secondary water flow channel having water outlets disposedalong the length of the main water flow channel, intermediate theplurality of pressure-controlled drip irrigation emitter units.

In accordance with a preferred embodiment of the present invention theat least one secondary water flow channel includes at least one of aweeping hose and a sweat irrigation hose. Preferably, the at least onesecondary water flow channel has associated therewith at least onepressure reducing pathway, having outlets which correspond to the wateroutlets.

There is also provided in accordance with another preferred embodimentof the present invention drip irrigation apparatus including a mainwater flow channel having associated therewith along a length thereof aplurality of pressure-controlled drip irrigation emitter units, at leastone secondary water flow channel extending generally parallel to themain water flow channel and receiving water from at least one of theplurality of pressure-controlled drip irrigation emitter units and atleast one pressure-reducing pathway associated with each of the at leastone secondary water flow channel and distributed therealong, the atleast one pressure-reducing pathway having outlets disposed along thelength of the main water flow channel, intermediate the plurality ofpressure-controlled drip irrigation emitter units.

In accordance with a preferred embodiment of the present invention theoutlets are defined by welding. Preferably, the at least one pressurereducing pathway includes a series of discrete labyrinths each having aninlet and an outlet. Additionally, the discrete labyrinths are realizedby embossing of the at least one secondary water flow channel.Alternatively, the discrete labyrinths are realized by attachingdiscrete labyrinth elements to the at least one secondary water flowchannel.

In accordance with another preferred embodiment of the present inventionthe at least one pressure reducing pathway includes a generallycontinuous series of non-mutually communicating labyrinths, each havingan inlet and an outlet. Preferably, the non-mutually communicatinglabyrinths are realized by embossing of the at least one secondary waterflow channel. Additionally or alternatively, the inlet faces the atleast one secondary water flow channel and the outlet faces away fromthe at least one secondary water flow channel.

In accordance with yet another preferred embodiment of the presentinvention the at least one pressure reducing pathway includes agenerally continuous labyrinth, having multiple inlets and multipleoutlets. Preferably, the multiple outlets are generally evenly spaced oneither side of each of the multiple inlets. Additionally oralternatively, two of the multiple outlets are provided for each of themultiple inlets. As a further addition or alternative, the multipleinlets face the at least one secondary water flow channel and themultiple outlets face away from the at least one secondary water flowchannel.

In accordance with still another preferred embodiment of the presentinvention at least one of the plurality of pressure-controlled dripirrigation emitter units includes a low pressure leakage preventionfeature. Preferably, at least one of the plurality ofpressure-controlled drip irrigation emitter units includes an inletaperture, a raised wall having a rim, the raised wall and the rimsurrounding the inlet aperture and an elastic element operative to bedisplaced when water pressure in the main water flow channel exceeds apredetermined threshold, and to be in sealed engagement with the rim ofthe raised wall when water pressure in the main water flow channel doesnot exceed the predetermined threshold. Additionally or alternatively,at least one of the plurality of pressure-controlled drip irrigationemitter units includes two mutually sealed portions.

In accordance with a further preferred embodiment of the presentinvention a first one of the two mutually sealed portions includes acircumferential raised elongate portion and an internal raised elongateportion extending between two sections of the at least onepressure-reducing pathway, and a second one of the two mutually sealedportions includes a circumferential elongate recess and an internalelongate recess, the two mutually sealed portions being sealed byengagement of the raised elongate portions with the elongate recesses.Preferably, the raised elongate portions have a generally triangularcross section, and the elongate recesses have a generally rectangularcross section. Additionally or alternatively, the two mutually sealedportions are sealed ultrasonically.

In accordance with a yet further preferred embodiment of the presentinvention the two mutually sealed portions are sealed ultrasonicallyalong the raised elongate portions and the elongate recesses.Preferably, at least one of the two mutually sealed portions and the atleast one pressure reducing pathway is not deformed by ultrasonicsealing of the raised elongate portions and the elongate recesses.Additionally or alternatively, dimensions of at least one of the twomutually sealed portions and the at least one pressure reducing pathwayare not changed by ultrasonic sealing of the raised elongate portionsand the elongate recesses.

In accordance with a still further preferred embodiment of the presentinvention the at least one pressure reducing pathway maintains itsfunctionality even when sealing between inwardly facing sides of the twomutually sealed portions is incomplete. Preferably, the first one of thetwo mutually sealed portions includes a circumferential raised wall andan internal raised wall having a protrusion therebetween, the protrusionbeing operative to at least partially prevent particular matter fromflowing into the at least one pressure reducing pathway.

In accordance with an additional preferred embodiment of the presentinvention the raised wall includes a non-circular wall, and the rim isconfigured such that at a predetermined threshold pressure across theelastic element, the elastic element transitions from generally completecircumferential disengagement with the rim to generally completecircumferential engagement with the rim. Preferably, the rim isconfigured such that at a second predetermined threshold pressure acrossthe elastic element, the elastic element transitions from generallycomplete circumferential engagement with the rim to generally completecircumferential disengagement with the rim. Additionally oralternatively the rim of the non-circular wall is non-planar.

In accordance with another preferred embodiment of the present inventionthe main water flow channel is defined by welding of one elongate edgeof a sheet to an interior location therealong. Preferably, the at leastone secondary water flow channel is defined by welding of anotherelongate edge of the sheet to a labyrinth defining strip which is weldedto the sheet at an exterior location therealong.

In accordance with yet another preferred embodiment of the presentinvention the main water flow channel is defined by welding of first andsecond elongate edges of a first sheet at a seam location. Preferably,the at least one secondary water flow channel is defined by welding of afirst elongate edge of a second sheet to the first elongate edge of thefirst sheet at the seam location and by welding a second elongate edgeof the second sheet to a labyrinth defining strip which is welded to thefirst sheet at an exterior location therealong.

In accordance with still another preferred embodiment of the presentinvention the main water flow channel is defined by an elongate tube.Preferably, the at least one secondary water flow channel is defined bywelding of a first elongate edge of a sheet to the elongate tube at afirst exterior location therealong and by welding of a second elongateedge of the sheet to a labyrinth defining strip which is welded to theelongate tube at a second exterior location therealong. Alternatively,the at least one secondary water flow channel is defined by welding of afirst elongate edge of a sheet to the elongate tube at a first exteriorlocation therealong and by welding of a second elongate edge of thesheet to the elongate tube at a second exterior location therealong, thesheet having a labyrinth defining strip welded at a surface thereofwhich faces an exterior-surface of the elongate tube.

As a further alternative, the at least one secondary flow channel isdefined by a second elongate tube surrounding the elongate tube, thesecond elongate tube having welded at a first location of an interiorsurface thereof a labyrinth defining strip and being welded at a secondlocation of the interior surface thereof to an outer surface of theelongate tube.

In accordance with a further preferred embodiment of the presentinvention the main water flow channel has welded at an interior locationtherealong at least one of the plurality of pressure-controlled dripirrigation emitter unit. Preferably, the at least one secondary waterflow channel includes material having at least one of weeping hosefunctionality and sweat irrigation functionality.

There is further provided in accordance with a further preferredembodiment of the present invention a pressure-controlled dripirrigation emitter element including a water inlet, an inlet controlchamber receiving water from the water inlet via an inlet aperture, apressure reducing pathway receiving water from the inlet controlchamber, an outlet control chamber receiving water from the pressurereducing pathway, an elastic element separating the inlet controlchamber and the outlet control chamber and a non-circular wallsurrounding the inlet aperture and having a rim, the rim beingconfigured such that at a predetermined threshold pressure across theelastic element, the elastic element transitions from generally completecircumferential disengagement with the rim to generally completecircumferential engagement with the rim.

There is additionally provided in accordance with an additionalpreferred embodiment of the present invention a pressure-controlled dripirrigation emitter element including a water inlet, an inlet controlchamber receiving water from the water inlet via an inlet aperture, apressure reducing pathway receiving water from the inlet controlchamber, an outlet control chamber receiving water from the pressurereducing pathway and an elastic element separating the inlet controlchamber and the outlet control chamber, the inlet control chamber, theoutlet control chamber and the pressure reducing pathway being definedby ultrasonic sealing of first and second emitter element portions in amanner such that the dimensions of the pressure reducing pathway are notaffected.

In accordance with a preferred embodiment of the present invention theinlet aperture is surrounded by a non-circular wall having a rim, therim being configured such that at a predetermined threshold pressureacross the elastic element, the elastic element transitions fromgenerally complete circumferential disengagement with the rim togenerally complete circumferential engagement with the rim. Preferably,the rim is configured such that at a second predetermined thresholdpressure across the elastic element, the elastic element transitionsfrom generally complete circumferential engagement with the rim togenerally complete circumferential disengagement with the rim.

In accordance with another preferred embodiment of the present inventionthe rim of the non-circular wall is non-planar. Preferably, one of thefirst and second emitter element portions includes a raised elongateportion and another of the first and second emitter element portionsincludes a corresponding elongate recess, the raised elongate portionand the elongate recess being ultrasonically welded together.Additionally or alternatively, the raised elongate portion has agenerally triangular cross section and the elongate recess has agenerally rectangular cross section.

In accordance with still another preferred embodiment of the presentinvention the one of the first and second emitter element portions alsoincludes an internal raised elongate portion extending between twosections of the pressure-reducing pathway, and the another of the firstand second emitter element portions also includes a correspondinginternal elongate recess, the internal raised elongate portion and theinternal elongate recess being ultrasonically welded together.Preferably, the internal raised elongate portion has a generallytriangular cross section and the internal elongate recess has agenerally rectangular cross section.

In accordance with yet another preferred embodiment of the presentinvention the pressure reducing pathway maintains its functionality evenwhen sealing between inwardly facing sides of the two mutually sealedportions is incomplete. Preferably, one of the first and second emitterelement portions includes a circumferential raised wall and an internalraised wall having a protrusion therebetween, the protrusion beingoperative to at least partially prevent particular matter from flowinginto the pressure reducing pathway.

There is also provided in accordance with another preferred embodimentof the present invention a pressure-controlled deep irrigation emitterelement disposed along an interior wall of a water supply tube includinga water inlet coupled to the interior wall of the water supply tube, aninlet control chamber receiving water from the water inlet via an inletaperture, a pressure reducing pathway receiving water from the inletcontrol chamber, the pressure reducing pathway being separated from theinterior wall of the water supply tube, an outlet control chamberreceiving water from the pressure reducing pathway via a pressurereducing pathway outlet passage and an elastic element separating theinlet control chamber and the outlet control chamber, the pressurereducing pathway outlet passage extending from the pressure reducingpathway, along a pathway extending between the emitter element and theinterior wall of the water supply tube, and to the outlet controlchamber.

In accordance with a preferred embodiment of the present invention theinlet aperture is surrounded by a non-circular wall having a rim, therim being configured such that at a predetermined threshold pressureacross the elastic element, the elastic element transitions fromgenerally complete circumferential disengagement with the rim togenerally complete circumferential engagement with the rim. Preferably,the rim is configured such that at a second predetermined thresholdpressure across the elastic element, the elastic element transitionsfrom generally complete circumferential engagement with the rim togenerally complete circumferential disengagement with the rim.

In accordance with another preferred embodiment of the present inventionthe rim of the non-circular wall is non-planar. Preferably, the inletcontrol chamber, the outlet control chamber and the pressure reducingpathway are defined by ultrasonic sealing of first and second emitterelement portions in a manner such that the dimensions of the pressurereducing pathway are not affected. Additionally or alternatively, thefirst and second emitter element portions includes a raised elongateportion and another of the first and second emitter element portionsincludes a corresponding elongate recess, the raised elongate portionand the elongate recess being ultrasonically welded together.

In accordance with yet another preferred embodiment of the presentinvention the raised elongate portion has a generally triangular crosssection and the elongate recess has a generally rectangular crosssection. Preferably, the one of the first and second emitter elementportions also includes an internal raised elongate portion extendingbetween two sections of the pressure-reducing pathway, and the anotherof the first and second emitter element portions also includes acorresponding internal elongate recess, the internal raised elongateportion and the internal elongate recess being ultrasonically weldedtogether. Additionally or alternatively, the internal raised elongateportion has a generally triangular cross section and the internalelongate recess has a generally rectangular cross section.

In accordance with a further preferred embodiment of the presentinvention the pressure reducing pathway maintains its functionality evenwhen sealing between inwardly facing sides of the two mutually sealedportions is incomplete. Preferably, one of the first and second emitterelement portions includes a circumferential raised wall and an internalraised wall, having a protrusion therebetween, the protrusion beingoperative to at least partially prevent particular matter from flowinginto the pressure reducing pathway.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified, general schematic illustration of dripirrigation apparatus constructed and operative in accordance with apreferred embodiment of the present invention;

FIGS. 2A and 2B are simplified pictorial illustrations of first andsecond sides of a first portion of a drip irrigation emitter elementuseful in the drip irrigation apparatus of FIG. 1;

FIGS. 3A and 3B are simplified pictorial illustrations of first andsecond sides of a second portion of the drip irrigation emitter elementuseful in the drip irrigation apparatus of FIG. 1;

FIG. 4 is a first simplified exploded view illustration of the dripirrigation emitter element of FIGS. 2A-3B;

FIG. 5 is a first simplified assembled view illustration of the dripirrigation emitter element of FIG. 4;

FIG. 6 is a second simplified exploded view illustration of the dripirrigation emitter element of FIGS. 2A-5;

FIG. 7 is a second simplified assembled view illustration of the dripirrigation emitter element of FIG. 6;

FIG. 8 is a simplified sectional illustration of the drip irrigationemitter element of FIGS. 2A-7, taken along section lines VIII-VIII inFIG. 5, the drip irrigation emitter element being placed inside a dripirrigation line of the general type shown in FIG. 1;

FIG. 9 is a simplified sectional illustration of the drip irrigationemitter element of FIGS. 2A-7, taken along section lines IX-IX in FIG.5, the drip irrigation emitter element being placed inside a dripirrigation line of the general type shown in FIG. 1;

FIG. 10 is a simplified sectional illustration of the drip irrigationemitter element of FIGS. 2A-7, taken along section lines X-X in FIG. 5,the drip irrigation emitter element being placed inside a dripirrigation line of the general type shown in FIG. 1;

FIGS. 11A, 11B, 11C and 11D are simplified illustrations of a problem inthe operation of prior art pressure-controlled anti-leakage dripirrigation emitters, FIG. 11A being a simplified not-to-scale pictorialillustration, FIGS. 11B and 11C being sectional illustrations takenalong respective section lines XIB-XIB and XIC-XIC in FIG. 11A, and FIG.11D being a superposition of portions of FIGS. 11B and 11C;

FIGS. 12A, 12B, 12C and 12D are simplified illustrations of a solutionto the problem in the operation of prior art pressure-controlledanti-leakage drip irrigation emitters as shown in FIGS. 11A-11D, FIG.12A being a simplified not-to-scale pictorial illustration, FIGS. 12Band 12C being sectional illustrations taken along respective sectionlines XIIB-XIIB and XIIC-XIIC in FIG. 12A, and FIG. 12D being asuperposition of portions of FIGS. 12B and 12C;

FIGS. 13A, 13B, 13C and 13D are generally to-scale simplifiedillustrations which correspond to FIGS. 12B and 12C in the context ofthe drip irrigation emitter element of FIGS. 2A-10, FIGS. 13A and 13Bshowing a first operative orientation of the drip irrigation emitterelement and FIGS. 13C and 13D showing a second operative orientation ofthe drip irrigation emitter element;

FIGS. 14A, 14B, 14C and 14D are simplified illustrations of anothersolution to the problem in the operation of prior artpressure-controlled anti-leakage drip irrigation emitters as shown inFIGS. 11A-11D, FIG. 14A being a simplified not-to-scale pictorialillustration, FIGS. 14B and 14C being sectional illustrations takenalong respective section lines XIVB-XIVB and XIVC-XIVC in FIG. 14A, andFIG. 14D being a superposition of portions of FIGS. 14B and 14C;

FIGS. 15A, 15B, 15C and 15D are generally to-scale simplifiedillustrations which correspond to FIGS. 14B and 14C in the context ofthe drip irrigation emitter element of FIGS. 2A-10, FIGS. 15A and 15Bshowing a first operative orientation of the drip irrigation emitterelement and FIGS. 15C and 15D showing a second operative orientation ofthe drip irrigation emitter element;

FIGS. 16A, 16B, 16C and 16D are simplified sectional illustrations ofdrip irrigation apparatus constructed and operative in accordance with apreferred embodiment of the present invention, taken at locationsindicated by respective arrows A, B, C and D in the general schematicillustration of FIG. 1;

FIGS. 17A, 17B, 17C and 17D are simplified sectional illustrations ofdrip irrigation apparatus constructed and operative in accordance withanother preferred embodiment of the present invention, taken atlocations indicated by respective arrows A, B, C and D in the generalschematic illustration of FIG. 1;

FIGS. 18A, 18B, 18C and 18D are simplified sectional illustrations ofdrip irrigation apparatus constructed and operative in accordance withyet another preferred embodiment of the present invention, taken atlocations indicated by respective arrows A, B, C and D in the generalschematic illustration of FIG. 1;

FIGS. 19A, 19B, 19C and 19D are simplified sectional illustrations ofdrip irrigation apparatus constructed and operative in accordance withstill another preferred embodiment of the present invention, taken atlocations indicated by respective arrows A, B, C and D in the generalschematic illustration of FIG. 1; and

FIGS. 20A, 20B, 20C and 20D are simplified sectional illustrations ofdrip irrigation apparatus constructed and operative in accordance with afurther preferred embodiment of the present invention, taken atlocations indicated by respective arrows A, B, C and D in the generalschematic illustration of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a simplified, generalschematic illustration of drip irrigation apparatus constructed andoperative in accordance with a preferred embodiment of the presentinvention. FIG. 1 shows a main water flow channel 100 having disposed atlongitudinally spaced locations therealong, typically separated fromeach other by approximately one meter, a plurality ofpressure-controlled drip irrigation emitter elements 102, whichpreferably include a low pressure leakage prevention feature. Each dripirrigation emitter element 102 provides a pressure-compensated liquidflow output to a secondary water flow channel 104, which extendsgenerally parallel to main water flow channel 100, via apressure-compensated emitter element output aperture 106 formed in acommon wall 108, joining main water flow channel 100 and secondary waterflow channel 104.

At least one longitudinally spaced secondary water flow channellabyrinth 110 communicates with secondary water flow channel 104 andprovides a reduced pressure output at multiple water outlets 112 whichcommunicate with the outside of the secondary water flow channel 104.Preferably a plurality of inlets 114 are provided to the at least onelongitudinally spaced secondary water flow channel labyrinth 110 alongthe length thereof. Outlets 112 and inlets 114 are typically defined bywelding or by other manufacturing techniques. Typically water outlets112 are separated from each other by 10 cm. Alternatively, secondarywater flow channel 104 may be a weeping hose, such as a weeping hose ofthe type described in U.S. Pat. No. 5,299,885, the content of which isincorporated herein by reference, or such as an Aquapore weeping hosecommercially available from Aquapore Moisture Systems, Inc. of Phoenix,Ariz. Alternatively, secondary water flow channel 104 may be any type ofhose suitable for sweat irrigation.

FIG. 1 includes five enlargements showing five alternative labyrinthstructures. An enlargement designated by Roman numeral I shows the atleast one longitudinally spaced secondary water flow channel labyrinth110 implemented as a series of discrete labyrinths 116, each having aninlet 118 and an outlet 120. The discrete labyrinths 116 may be realizedby embossing of the secondary water flow channel 104 or alternatively byattaching discrete labyrinth elements to the secondary water flowchannel 104.

An enlargement designated by Roman numeral II shows the at least onelongitudinally spaced secondary water flow channel labyrinth 110implemented as a generally continuous series of non-mutuallycommunicating labyrinths 122, each having an inlet 124 and an outlet126. The generally continuous series of non-mutually communicatinglabyrinths 122 may be realized by embossing of the secondary water flowchannel 104.

An enlargement designated by Roman numeral III shows the at least onelongitudinally spaced secondary water flow channel labyrinth 110implemented as a generally continuous labyrinth 128, having multipleinlets 130 and outlets 132. Preferably, the outlets 132 are generallyevenly spaced on either side of each inlet 130. Typically two outlets132 are provided for each inlet 130.

An enlargement designated by Roman numeral IV shows the at least onelongitudinally spaced secondary water flow channel labyrinth 110implemented as a generally continuous series of non-mutuallycommunicating labyrinths 142, each having an inlet 144 facing thesecondary water flow channel 104 and an outlet 146 facing in an oppositedirection, away from the secondary water flow channel 104. The generallycontinuous series of non-mutually communicating labyrinths 142 may berealized by embossing of the secondary water flow channel 104.

An enlargement designated by Roman numeral V shows the at least onelongitudinally spaced secondary water flow channel labyrinth 110implemented as a generally continuous labyrinth 148, having multipleinlets 150 facing the secondary water flow channel 104 and multipleoutlets 152 facing in an opposite direction, away from the secondarywater flow channel 104. Preferably, the outlets 152 are generally evenlyspaced on either side of each inlet 150. Typically two outlets 152 areprovided for each inlet 150.

Reference is now made to FIGS. 2A and 2B, which are simplified pictorialillustrations of first and second sides of a first portion of a dripirrigation emitter element useful in the drip irrigation apparatus ofFIG. 1, to FIGS. 3A and 3B, which are simplified pictorial illustrationsof first and second sides of a second portion of the drip irrigationemitter element useful in the drip irrigation apparatus of FIG. 1, toFIG. 4, which is a first simplified exploded view illustration of thedrip irrigation emitter element of FIGS. 2A-3B, to FIG. 5, which is afirst simplified assembled view illustration of the drip irrigationemitter element of FIG. 4, to FIG. 6, which is a second simplifiedexploded view illustration of the drip irrigation emitter element ofFIGS. 2A-5, to FIG. 7, which is a second simplified assembled viewillustration of the drip irrigation emitter element of FIG. 6, and toFIGS. 8, 9 and 10, which are simplified sectional illustrations of thedrip irrigation emitter element of FIGS. 2A-7 when placed inside a dripirrigation line of the general type shown in FIG. 1.

Turning initially to FIGS. 4-7, water from main water flow channel 100(FIG. 1) passes a water filtering grid 200, as indicated by an arrow201, and through an inlet aperture 202, which aperture is surrounded bya raised wall 204. When the pressure of the water in main water flowchannel 100 exceeds a predetermined threshold, preferably 0.5Atmospheres, the water displaces a generally rectangular planar elasticelement 206, which, in the absence of such pressure, lies in sealedengagement with a rim 208 of raised wall 204.

An inlet control chamber 209 is defined by rim 208, a surface 210 andgenerally rectangular planar elastic element 206. Displacement ofgenerally rectangular planar elastic element 206 from sealed engagementwith rim 208 allows water to flow through aperture 202 into inletcontrol chamber 209, as described further hereinbelow with reference toFIGS. 13A-13D, along surface 210, as indicated by arrows 211, and via alongitudinal recess 212 formed in surface 210 to an inlet 214 of alabyrinthine passageway 216. The structure of the labyrinthinepassageway 216 is seen from additional consideration of FIGS. 2A and 3Bwhich illustrate facing, mutually sealed sides 220 and 222 of respectiveportions 224 and 226 of a drip irrigation emitter element 230, useful asthe drip irrigation emitter element 102 (FIG. 1).

Portions 224 and 226 of drip irrigation emitter element 230 are sealedtogether at a circumferential raised elongate portion 232 to which isconnected an internal raised elongate portion 234, which extends betweentwo sections 236 and 238 of pressure-reducing labyrinthine passageway216. Elongate portions 232 and 234 extend from side 222 of portion 226and sealingly engage correspondingly located elongate recesses 242 and244 formed on side 220 of portion 224. Preferably, elongate portions 232and 234 have a generally triangular cross section as seen in theenlarged portion of FIG. 6, and recesses 242 and 244 have a generallyrectangular cross section as seen in the enlarged portion of FIG. 4.

The labyrinthine passageway 216 is defined by a series of tooth-likeprotrusions 250 which extend from a surface 251 and have a top surface252. In the assembled drip irrigation emitter element 230, when elongateportions 232 and 234 are sealed to respective elongate recesses 242 and244, surfaces 210 and 252 lie in mutually touching, preferably sealedengagement. Preferably, the sealing is effected ultrasonically and thedimensions of the circumferential raised elongate portion 232, theinternal raised elongate portion 234 and corresponding recesses 242 and244 are such that ultrasonic sealing thereof does not deform or affectthe dimensions or mutual engagement of surfaces 210 and 252 andparticularly does not affect the dimensions of the labyrinthinepassageway 216.

It is appreciated that sealing between internal elongate portion 234 andcorresponding elongate recess 244 is provided such that in the event ofincomplete sealing between surfaces 210 and 252, water will not bypassmuch of the labyrinthine passageway 216 from section 236 to section 238and from the region lying between surface 210 and elastic element 206 tosection 238.

The water flows through the labyrinthine pathway 216 to a labyrinthinepathway outlet 260 and the water pressure is correspondingly reduced byabout 0.4 Atmospheres, typically from a line pressure of 0.5 to 4Atmospheres.

Reference is now made additionally to FIGS. 8-10, which illustrate aside 270, shown with particular clarity in FIG. 3A, of portion 226 ofelement 230, being sealed to an interior wall surface 272 of a watersupply pipe 274, useful as main water flow channel 100 (FIG. 1).

As seen in FIGS. 3A, 4 and 5, a circumferential raised wall 280 and aninternal raised wall 282 define respective rims 284 and 286 which areheat welded to interior wall surface 272 (FIG. 8).

Water passes through labyrinthine pathway outlet 260 and enters achamber 290, from which it exits via an outlet 292 and enters an outletcontrol chamber 294, formed at side 222 of portion 226 and sealed bygenerally rectangular planar elastic element 206. Elastic element 206 issupported by a surface 296 which surrounds outlet control chamber 294.

As seen particularly in FIGS. 8-10, generally rectangular planar elasticelement 206 governs water flow through an outlet 300 of outlet controlchamber 294, as a function of the line pressure applied to generallyrectangular planar elastic element 206 at a surface 302 thereof, whichsurface engages rim 208. Outlet 300 is typically in the form of acircular hole. Preferably, a shallow slot 304, which is seen withparticular clarity in FIGS. 3B and 6, is provided in communication withthe outlet 300, to assist in providing efficient pressure responsiveflow control of water passing through the outlet 300.

Water passing through outlet 300 enters a volume 310, defined between asurface 312 of side 270 and surface 272 of water supply pipe 274, andthen passes to a volume 314, defined between a surface 316 of side 270and surface 272 of water supply pipe 274, via a partial obstruction 320.The partial obstruction 320 is provided for helping to preventparticulate matter from passing back from volume 314 into volume 310.

Water leaves volume 314 via an opening 322 formed in water supply pipe274, which opening corresponds to pressure-compensated emitter elementoutput aperture 106 (FIG. 1).

Reference is now made to FIGS. 11A, 11B, 11C and 11D, which areillustrations of a problem in the operation of prior artpressure-controlled anti-leakage drip irrigation emitters, FIG. 11Abeing a simplified not-to-scale pictorial illustration, FIGS. 11B and11C being sectional illustrations taken along respective section linesXIB-XIB and XIC-XIC in FIG. 11A, and FIG. 11D being a superposition ofportions of FIGS. 11B and 11C.

Reference is made to prior art pressure-controlled anti-leakage dripirrigation emitters which employ a non-square, rectangular elasticelement 380 which is secured along its non-square, rectangular peripheryand a circular raised wall 382 surrounding an inlet aperture 384. Whenthe liquid pressure underlying the rectangular elastic element 380 issuch that an underside surface 386 of the elastic element 380 barelytouches portions 388 of the top surface 390 of wall 382, which lieclosest to an edge of the elastic element 380, the underside surface 386does not touch portions 392 of the top surface 390 which lie furtherfrom an edge of the elastic element 380. This can be seen withparticular clarity in FIGS. 11B and 11C as well as in the superpositionof FIG. 11D.

The present inventors have understood that this constitutes a problem inpressure-controlled anti-leakage drip irrigation emitters, since thereexists a range of pressures at which the inlet aperture is not fullyopen or fully closed by the elastic element 380, resulting in a leakagesituation. Furthermore, the circumferentially incomplete contact betweenthe elastic element 380 and top surface 390 of wall 382 surrounding theinlet aperture 384 inhibits sealing of the inlet aperture at even lowerpressures, inasmuch as any contact between the elastic element 380 andany location on top surface 390 increases the amount of force requiredto establish further and full contact. Accordingly, the level of fluidpressure underlying the elastic element 380 required to achieve sealingof the inlet aperture is much lower than would otherwise be required toseal the inlet aperture, and undesired leakage occurs followingtermination of water supply to the drip irrigation line and followinginitial supply of water to the drip irrigation line.

Reference is now made to FIGS. 12A, 12B, 12C and 12D, which areillustrations of a solution to the problem in the operation of prior artpressure-controlled anti-leakage drip irrigation emitters as shown inFIGS. 11A-11D and discussed hereinabove, FIG. 12A being a simplifiednot-to-scale pictorial illustration, FIGS. 12B and 12C being sectionalillustrations taken along respective section lines XIIB-XIIB andXIIC-XIIC in FIG. 12A, and FIG. 12D being a superposition of portions ofFIGS. 12B and 12C.

As seen in FIGS. 12A-12D, a non-circular raised wall 400 surrounds aninlet aperture 402. In this case, in accordance with a preferredembodiment of the present invention, when the liquid pressure underlyinga rectangular elastic element 406 is such that an underside surface 408of the elastic element 406 barely touches portions 410 of the topsurface 412 of wall 400, which lie closest to an edge of the elasticelement 406, the underside surface 408 simultaneously or nearlysimultaneously also barely touches portions 414 of the top surface 412which lie further from an edge of the elastic element. This can be seenwith particular clarity in FIGS. 12B and 12C as well as in thesuperposition of FIG. 12D.

The present inventors have understood that this solves the problem inprior art pressure-controlled anti-leakage drip irrigation emitterswhich was discussed above with reference to FIGS. 11A -11D, by greatlyreducing or eliminating the range of pressures at which the inletaperture is not fully open or fully closed by the elastic element 380,resulting in a leakage situation. Furthermore, the circumferentiallycomplete contact between the elastic element 406 and top surface 412 ofwall 400 surrounding the inlet aperture 402 enhances sealing of theinlet aperture. Accordingly, the level of fluid pressure underlying theelastic element 406 required to achieve sealing of the inlet aperturecan be higher than would otherwise be required to seal the inletaperture in the prior art. Thus, scaling takes place followingtermination of water supply to the drip irrigation line at a higher linepressure and thus enables efficient use of the drip irrigation line overa greater range of variation of height than was possible in the priorart. Any leakage that occurs, takes place over a substantially shorterperiod following termination of water supply to the drip irrigationline, and over a shorter period following initial supply of water to thedrip irrigation line, than in the prior art.

Reference is now made to FIGS. 13A, 13B, 13C and 13D, which aregenerally to-scale simplified illustrations which correspond to FIGS.12B and 12C in the context of the drip irrigation emitter element ofFIGS. 2A-10, FIGS. 13A and 13B showing a first operative orientation ofthe drip irrigation emitter element and FIGS. 13C and 13D showing asecond operative orientation of the drip irrigation emitter element.

FIGS. 13A and 13B are generally to-scale simplified illustrations whichcorrespond to FIGS. 12B and 12C in the context of the drip irrigationemitter element of FIGS. 2A-10. The non-circular configuration of theinlet aperture 402 (FIGS. 12A-12D) can be seen by considering theseparations between portions of the rim 208 in respective FIGS. 13A (410in FIG. 12B) and 13B (414 in FIG. 12C), which represent mutuallyperpendicular cross-sections of the drip irrigation emitter element. Theindicated angles illustrate the angular engagement between the elasticelement 206 and rim 208 of the wall 204 of the inlet aperture 202.

FIGS. 13A and 13B show the drip irrigation emitter element in a closedoperative orientation in which surface 302 of elastic element 206 liesin sealed engagement with rim 208, thereby preventing the flow of waterfrom inlet aperture 202 into inlet control chamber 209. FIGS. 13C and13D show the drip irrigation emitter element in an open operativeorientation in which surface 302 of elastic element 206 is displacedfrom sealed engagement with rim 208, thereby allowing the flow of waterfrom inlet aperture 202 into inlet control chamber 209.

Transition of the drip irrigation emitter element from the closedoperative orientation of FIGS. 13A and 13B to the open operativeorientation of FIGS. 13C and 13D occurs when the water pressure in mainwater flow channel 100 (FIG. 1) exceeds a predetermined thresholdpreferably of 0.5 Atmospheres. Transition of the drip irrigation emitterelement from the open operative orientation of FIGS. 13C and 13D to theclosed operative orientation of FIGS. 13A and 13B occurs when the waterpressure in main water flow channel 100 (FIG. 1) drops below apredetermined threshold preferably of 0.2 Atmospheres.

Reference is now made to FIGS. 14A, 14B, 14C and 14D, which aresimplified illustrations of another solution to the problem in theoperation of prior art pressure-controlled anti-leakage drip irrigationemitters as shown in FIGS. 11A -11D, FIG. 14A being a simplifiednot-to-scale pictorial illustration, FIGS. 14B and 14C being sectionalillustrations taken along respective section lines XIVB-XIVB andXIVC-XIVC in FIG. 14A, and FIG. 14D being a superposition of portions ofFIGS. 14B and 14C.

As seen in FIGS. 14A-14D, a non-circular raised wall 460 having anon-uniform wall height, surrounds an inlet aperture 462. It isappreciated that the inlet aperture 462 is typically of somewhat smallerdimensions than that of FIGS. 2A-10 and 12A -13B. The wall 460 isconfigured to be lowest at portions 464 of a top surface 466 of wall460, which lie closest to an edge of an elastic element 470 and highestat portions 472 of the top surface 466 of wall 460, which lie furthestfrom an edge of the elastic element 470.

In this case, in accordance with another preferred embodiment of thepresent invention, when the liquid pressure underlying the rectangularelastic element 470 is such that an underside surface 474 of the elasticelement 470 barely touches portions 464 of the top surface 466 of wall460, the underside surface 474 simultaneously or nearly simultaneouslyalso barely touches portions 472 of the top surface 466. This can beseen with particular clarity in FIGS. 14B and 14C as well as in thesuperposition of FIG. 14D.

The present inventors have understood that this embodiment also solvesthe problem in prior art pressure-controlled anti-leakage dripirrigation emitters which was discussed above with reference to FIGS.11A-11D, by greatly reducing or eliminating the range of pressures atwhich the inlet aperture is not fully open or fully closed by theelastic element 380 (FIGS. 11A & 11B), resulting in a leakage situation.Furthermore, the circumferentially complete contact between the elasticelement 470 and top surface 466 of wall 460 surrounding the inletaperture 462 enhances sealing of the inlet aperture. Accordingly, thelevel of fluid pressure underlying the elastic element 470 required toachieve sealing of the inlet aperture can be higher than would otherwisebe required to seal the inlet aperture in the prior art, and any leakagethat occurs takes place over a substantially shorter period followingtermination of water supply to the drip irrigation line and over ashorter period following initial supply of water to the drip irrigationline than in the prior art. This enables efficient use of the dripirrigation line over a greater range of variation of height than waspossible in the prior art.

Reference is now made to FIGS. 15A, 15B, 15C and 15D which are generallyto-scale simplified illustrations which correspond to FIGS. 14B and 14Cin the general context of the drip irrigation emitter element of FIGS.2A-10, but having a somewhat smaller inlet aperture 202. Thenon-circular configuration of the inlet aperture 202 and its non-uniformwall height (FIGS. 14A-14D) can be seen by considering the separationsbetween and variations in height of portions of the rim 208 in FIGS. 15Aand 15C (464 in FIG. 14B) and in FIGS. 15B and 15D (472 in FIG. 14C),which represent mutually perpendicular cross-sections of the dripirrigation emitter element. The indicated angles in FIGS. 15A and 15Billustrate the angular engagement between the elastic element 206 andrim 208 of the wall 204 of the inlet aperture 202.

FIGS. 15A and 15B show the drip irrigation emitter element in a closedoperative orientation in which surface 302 of elastic element 206 liesin sealed engagement with rim 208, thereby preventing the flow of waterfrom inlet aperture 202 into inlet control chamber 209. FIGS. 15C and15D show the drip irrigation emitter element in an open operativeorientation in which surface 302 of elastic element 206 is displacedfrom sealed engagement with rim 208, thereby allowing the flow of waterfrom inlet aperture 202 into inlet control chamber 209.

Transition of the drip irrigation emitter element from the closedoperative orientation of FIGS. 15A and 15B to the open operativeorientation of FIGS. 15C and 15D occurs when the water pressure in mainwater flow channel 100 (FIG. 1) exceeds a predetermined threshold ofpreferably 0.5 Atmospheres. Transition of the drip irrigation emitterelement from the open operative orientation of FIGS. 15C and 15D to theclosed operative orientation of FIGS. 15A and 15B occurs when the waterpressure in main water flow channel 100 (FIG. 1) drops below apredetermined threshold of preferably 0.2 Atmospheres.

Reference is now made to FIGS. 16A, 16B, 16C and 16D, which aresimplified sectional illustrations of drip irrigation apparatusconstructed and operative in accordance with a preferred embodiment ofthe present invention, taken at locations indicated by respective arrowsA, B, C and D in the general schematic illustration of FIG. 1.

FIGS. 16A-16D show drip irrigation apparatus of the general type shownin FIG. 1, and more particularly of the type shown in enlargements IIand III in FIG. 1. FIGS. 16A-16D show drip irrigation apparatus of thetype shown in enlargement II of FIG. 1, formed of an elongate sheet ofplastic 500 to which drip irrigation emitter elements 502, preferably ofthe type described hereinabove with reference to FIGS. 2A-10, arewelded.

One elongate edge of sheet 500, designated by reference numeral 504, iswelded to an interior location of the sheet 500, which is designated byreference numeral 506, thereby to define a main water flow channel 508which corresponds to main water flow channel 100 (FIG. 1).

An opposite elongate edge of sheet 500, designated by reference numeral510 is welded at an exterior location of sheet 500, which is designatedby reference numeral 512, to a secondary water flow channellabyrinth-defining strip 514, which is also welded to sheet 500, so asto define a secondary water flow channel 516, and a secondary water flowchannel labyrinth 518.

Alternatively, strip 514 may have weeping hose functionality and/orsweat irrigation functionality, and in such a case, need not define alabyrinth.

FIG. 16A is a partially sectional, partially pictorial illustration,taken at arrows A-A in the general schematic illustration of FIG. 1 andalong the section lines A-A in enlargement II of FIG. 1, which sectionlines pass through a water inlet 520 of the drip irrigation emitterelement 502, which allows water to flow from main water flow channel508.

FIG. 16B is a partially sectional, partially pictorial illustration,taken at arrows B-B in the general schematic illustration of FIG. 1 andalong the section lines B-B in enlargement II of FIG. 1, which sectionlines pass through a water outlet 522 of the drip irrigation emitterelement 502, which allows water to flow into the secondary water flowchannel 516.

FIG. 16C is a partially sectional, partially pictorial illustration,taken at arrows C-C in the general schematic illustration of FIG. 1 andalong the section lines C-C in enlargement II of FIG. 1, which sectionlines pass through a water inlet 524 of the secondary water flow channellabyrinth 518, which allows water to flow from the secondary water flowchannel 516 into the secondary water flow channel labyrinth 518.

FIG. 16D is a partially sectional, partially pictorial illustration,taken at arrows D-D in the general schematic illustration of FIG. 1 andalong the section lines D-D in enlargement II of FIG. 1, which sectionlines pass through a water outlet 526 of the secondary water flowchannel labyrinth 518 which allows water to flow from the secondarywater flow channel labyrinth 518 to the atmosphere.

Reference is now made to FIGS. 17A, 17B, 17C and 17D, which aresimplified sectional illustrations of drip irrigation apparatusconstructed and operative in accordance with another preferredembodiment of the present invention, taken at locations indicated byrespective arrows A, B, C and D in the general schematic illustration ofFIG. 1.

FIGS. 17A-17D show drip irrigation apparatus of the general type shownin FIG. 1, and more particularly of the type shown in enlargements IIand III in FIG. 1. FIGS. 17A-17D show drip irrigation apparatus of thetype shown in enlargement II of FIG. 1, formed of an elongate sheet ofplastic 530 to which drip irrigation emitter elements 532, preferably ofthe type described hereinabove with reference to FIGS. 2A-10, arewelded.

The elongate edges of sheet 530, designated by reference numerals 534and 536, are welded together at a seam 538, thereby to define a mainwater flow channel 540 which corresponds to main water flow channel 100(FIG. 1).

An elongate edge 542 of an additional elongate sheet of plastic 544 iswelded at seam 538 to edge 534 of sheet 530. Alternatively, elongatesheet 544 may incorporate material having weeping hose functionalityand/or sweat irrigation functionality. An opposite elongate edge 546 ofsheet 544 is welded at an exterior location of sheet 530, which isdesignated by reference numeral 548, to a secondary water flow channellabyrinth-defining strip 550, which is also welded to sheet 530, so asto define a secondary water flow channel 552, and a secondary water flowchannel labyrinth 554. Alternatively, strip 550 may have weeping hosefunctionality and/or sweat irrigation functionality, and in such a case,need not define a labyrinth.

FIG. 17A is a partially sectional, partially pictorial illustration,taken at arrows A-A in the general schematic illustration of FIG. 1 andalong the section lines A—A in enlargement II of FIG. 1, which sectionlines pass through a water inlet 556 of the drip irrigation emitterelement 532, which allows water to flow from main water flow channel540.

FIG. 17B is a partially sectional, partially pictorial illustration,taken at arrows B-B in the general schematic illustration of FIG. 1 andalong the section lines B-B in enlargement II of FIG. 1, which sectionlines pass through a water outlet 558 of the drip irrigation emitterelement 532, which allows water to flow into the secondary water flowchannel 552.

FIG. 17C is a partially sectional, partially pictorial illustration,taken at arrows C-C in the general schematic illustration of FIG. 1 andalong the section lines C-C in enlargement II of FIG. 1, which sectionlines pass through a water inlet 560 of the secondary water flow channellabyrinth 554, which allows water to flow from the secondary water flowchannel 552 into the secondary water flow channel labyrinth 554.

FIG. 17D is a partially sectional, partially pictorial illustration,taken at arrows D-D in the general schematic illustration of FIG. 1 andalong the section lines D-D in enlargement II of FIG. 1, which sectionlines pass through a water outlet 562 of the secondary water flowchannel labyrinth 554 which allows water to flow from the secondarywater flow channel labyrinth 554 to the atmosphere.

Reference is now made to FIGS. 18A, 18B, 18C and 18D, which aresimplified sectional illustrations of drip irrigation apparatusconstructed and operative in accordance with yet another preferredembodiment of the present invention, taken at locations indicated byrespective arrows A, B, C and D in the general schematic illustration ofFIG. 1.

FIGS. 18A -18D show drip irrigation apparatus of the general type shownin FIG. 1, and more particularly of the type shown in enlargements IIand III in FIG. 1. FIGS. 18A-18D show drip irrigation apparatus of thetype shown in enlargement II of FIG. 1, formed of an elongate tube ofplastic 570, to an interior wall of which are welded drip irrigationemitter elements 572, preferably of the type described hereinabove withreference to FIGS. 2A-10. The plastic tube 570 defines a main water flowchannel 574 which corresponds to main water flow channel 100 (FIG. 1).

An elongate edge 576 of an elongate sheet of plastic 578 is welded totube 570 at an exterior location therealong, designated by referencenumeral 580. An opposite elongate edge 582 of sheet 578 is welded to asecondary water flow channel labyrinth-defining strip 584, which iswelded to tube 570 at an exterior location therealong, designated byreference numeral 586, so as to define a secondary water flow channel588, and a secondary water flow channel labyrinth 590.

Elongate sheet 578 may alternatively incorporate material having weepinghose functionality and/or sweat irrigation functionality. Strip 584 mayalternatively have weeping hose functionality and/or sweat irrigationfunctionality and in such a case, need not define a labyrinth. FIG. 18Ais a partially sectional, partially pictorial illustration, taken atarrows A-A in the general schematic illustration of FIG. 1 and along thesection lines A-A in enlargement II of FIG. 1, which section lines passthrough a water inlet 592 of the drip irrigation emitter element 572,which allows water to flow from main water flow channel 574.

FIG. 18B is a partially sectional, partially pictorial illustration,taken at arrows B-B in the general schematic illustration of FIG. 1 andalong the section lines B-B in enlargement II of FIG. 1, which sectionlines pass through a water outlet 594 of the drip irrigation emitterelement 572, which allows water to flow into the secondary water flowchannel 588.

FIG. 18C is a partially sectional, partially pictorial illustration,taken at arrows C-C in the general schematic illustration of FIG. 1 andalong the section lines C-C in enlargement II of FIG. 1, which sectionlines pass through a water inlet 596 of the secondary water flow channellabyrinth 590, which allows water to flow from the secondary water flowchannel 588 to the secondary water flow channel labyrinth 590.

FIG. 18D is a partially sectional, partially pictorial illustration,taken at arrows D-D in the general schematic illustration of FIG. 1 andalong the section lines D-D in enlargement II of FIG. 1, which sectionlines pass through a water outlet 598 of the secondary water flowchannel labyrinth 590, which allows water to flow from the secondarywater flow channel labyrinth 590 to the atmosphere.

Reference is now made to FIGS. 19A, 19B, 19C and 19D, which aresimplified sectional illustrations of drip irrigation apparatusconstructed and operative in accordance with still another preferredembodiment of the present invention, taken at locations indicated byrespective arrows A, B, C and D in the general schematic illustration ofFIG. 1.

FIGS. 19A-19D show drip irrigation apparatus of the general type shownin FIG. 1, and more particularly of the type shown in enlargements IVand V in FIG. 1. FIGS. 19A-19D show drip irrigation apparatus of thetype shown in enlargement IV of FIG. 1, formed of an elongate tube ofplastic 600, to an interior wall of which are welded drip irrigationemitter elements 602, preferably of the type described hereinabove withreference to FIGS. 2A-10. The plastic tube 600 defines a main water flowchannel 604 which corresponds to main water flow channel 100 (FIG. 1).

An elongate edge 606 of an elongate sheet of plastic 608 is welded totube 600 at an exterior location therealong, which is designated byreference numeral 610. An opposite elongate edge 612 of sheet 608 iswelded to tube 600 at another exterior location therealong, designatedby reference numeral 614, thereby defining a secondary water flowchannel 616. Welded to an interior facing surface of sheet 608 is asecondary water flow channel labyrinth-defining element 618, whichdefines a secondary water flow channel labyrinth 620.

Elongate sheet 608 may alternatively incorporate material having weepinghose functionality and/or sweat irrigation functionality, and in such acase, element 618 may be omitted.

FIG. 19A is a partially sectional, partially pictorial illustration,taken at arrows A-A in the general schematic illustration of FIG. 1 andalong the section lines A-A in enlargement IV of FIG. 1, which sectionlines pass through a water inlet 622 of the drip irrigation emitterelement 602, which allows water to flow from main water flow channel604.

FIG. 19B is a partially sectional, partially pictorial illustration,taken at arrows B-B in the corresponding schematic illustration of FIG.1 and along the section lines B -B in enlargement IV of FIG. 1, whichsection lines pass through a water outlet 624 of the drip irrigationemitter element 602, which allows water to flow into the secondary waterflow channel 616.

FIG. 19C is a partially sectional, partially pictorial illustration,taken at arrows C-C in the general schematic illustration of FIG. 1 andalong the section lines C-C in enlargement IV of FIG. 1, which sectionlines pass through a water inlet 626 of the secondary water flow channellabyrinth 620, which allows water to flow from the secondary water flowchannel 616 to the secondary water flow channel labyrinth 620.

FIG. 19D is a partially sectional, partially pictorial illustration,taken at arrows D-D in the general schematic illustration of FIG. 1 andalong the section lines D-D in enlargement IV of FIG. 1, which sectionlines pass through a water outlet 628 of the secondary water flowchannel labyrinth 620, which allows water to flow from the secondarywater flow channel labyrinth 620 to the atmosphere.

Reference is now made to FIGS. 20A, 20B, 20C and 20D, which aresimplified sectional illustrations of drip irrigation apparatusconstructed and operative in accordance with a further preferredembodiment of the present invention, taken at locations indicated byrespective arrows A, B, C and D in the general schematic illustration ofFIG. 1.

FIGS. 20A-20D show drip irrigation apparatus of the general type shownin FIG. 1, and more particularly of the type shown in enlargements IVand V in FIG. 1. FIGS. 20A-20D show drip irrigation apparatus of thetype shown in enlargement IV of FIG. 1, formed of an inner elongate tubeof plastic 650, to an interior wall of which are welded drip irrigationemitter elements 652, preferably of the type described hereinabove withreference to FIGS. 2A-10. The plastic tube 650 defines a main water flowchannel 654 which corresponds to main water flow channel 100 (FIG. 1).

An outer elongate plastic tube 656, which may be extruded over innerelongate tube 650, defines with an outer surface of inner elongate tube650 a secondary water flow channel 658. Tube 656 may or may not bejoined to tube 650.

Welded to an interior facing surface of tube 656 is a secondary waterflow channel labyrinth-defining element 660, which defines a secondarywater flow channel labyrinth 662. Tube 656 may alternatively incorporatematerial having weeping hose functionality and/or sweat irrigationfunctionality, and in such a case, element 660 may be omitted.

FIG. 20A is a partially sectional, partially pictorial illustration,taken at arrows A-A in the general schematic illustration of FIG. 1 andalong the section lines A-A in enlargement IV of FIG. 1, which sectionlines pass through a water inlet 664 of the drip irrigation emitterelement 652, which allows water to flow from main water flow channel654.

FIG. 20B is a partially sectional, partially pictorial illustration,taken at arrows B-B in the general schematic illustration of FIG. 1 andalong the section lines B-B in enlargement IV of FIG. 1, which sectionlines pass through a water outlet 666 of the drip irrigation emitterelement 652, which allow water to flow into the secondary water flowchannel 658.

FIG. 20C is a partially sectional, partially pictorial illustration,taken at arrows C-C in the general schematic illustration of FIG. 1 andalong the section lines C-C in enlargement IV of FIG. 1, which sectionlines pass through a water inlet 668 of the secondary water flow channellabyrinth 662, which allows water to flow from the secondary water nowchannel 658 to the secondary water flow channel labyrinth 662.

FIG. 20D is a partially sectional, partially pictorial illustration,taken at arrows D-D in the general schematic illustration of FIG. 1 andalong the section lines D-D in enlargement IV of FIG. 1, which sectionlines pass through a water outlet 670 of the secondary water flowchannel labyrinth 662, which allows water to flow from the secondarywater flow channel labyrinth 662 to the atmosphere.

It is appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of various featuresdescribed hereinabove as well as variations and modifications theretowhich would occur to a person of skill in the art upon reading the abovedescription and which are not in the prior art.

1. Drip irrigation apparatus comprising: a main water flow channelhaving associated therewith along a length thereof a plurality ofpressure-controlled drip irrigation emitter units; and at least onesecondary water flow channel extending generally parallel to said mainwater flow channel and receiving water from at least one of saidplurality of pressure-controlled drip irrigation emitter units, said atleast one secondary water flow channel having water outlets disposedalong the length of said main water flow channel, intermediate saidplurality of pressure-controlled drip irrigation emitter units.
 2. Dripirrigation apparatus according to claim 1 and wherein said at least onesecondary water flow channel comprises at least one of a weeping hoseand a sweat irrigation hose.
 3. Drip irrigation apparatus according toclaim 1 and wherein said at least one secondary water flow channel hasassociated therewith at least one pressure reducing pathway, havingoutlets which correspond to said water outlets.
 4. Drip irrigationapparatus comprising: a main water flow channel having associatedtherewith along a length thereof a plurality of pressure-controlled dripirrigation emitter units; at least one secondary water flow channelextending generally parallel to said main water flow channel andreceiving water from at least one of said plurality ofpressure-controlled drip irrigation emitter units; and at least onepressure-reducing pathway associated with each of said at least onesecondary water flow channel and distributed therealong, said at leastone pressure-reducing pathway having outlets disposed along the lengthof said main water flow channel, intermediate said plurality ofpressure-controlled drip irrigation emitter units.
 5. Drip irrigationapparatus according to claim 4 and wherein said outlets are defined bywelding.
 6. Drip irrigation apparatus according to claim 4 and whereinsaid at least one pressure reducing pathway comprises a series ofdiscrete labyrinths each having an inlet and an outlet.
 7. Dripirrigation apparatus according to claim 6 and wherein said discretelabyrinths are realized by embossing of said at least one secondarywater flow channel.
 8. Drip irrigation apparatus according to claim 6and wherein said discrete labyrinths are realized by attaching discretelabyrinth elements to said at least one secondary water flow channel. 9.Drip irrigation apparatus according to claim 4 and wherein said at leastone pressure reducing pathway comprises a generally continuous series ofnon-mutually communicating labyrinths, each having an inlet and anoutlet.
 10. Drip irrigation apparatus according to claim 9 and whereinsaid non-mutually communicating labyrinths are realized by embossing ofsaid at least one secondary water flow channel.
 11. Drip irrigationapparatus according to claim 9 and wherein said inlet faces said atleast one secondary water flow channel and said outlet faces away fromsaid at least one secondary water flow channel.
 12. Drip irrigationapparatus according to claim 4 and wherein said at least one pressurereducing pathway comprises a generally continuous labyrinth, havingmultiple inlets and multiple outlets.
 13. Drip irrigation apparatusaccording to claim 12 and wherein said multiple outlets are generallyevenly spaced on either side of each of said multiple inlets.
 14. Dripirrigation apparatus according to claim 12 and wherein two of saidmultiple outlets are provided for each of said multiple inlets.
 15. Dripirrigation apparatus according to claim 12 and wherein said multipleinlets face said at least one secondary water flow channel and saidmultiple outlets face away from said at least one secondary water flowchannel.
 16. Drip irrigation apparatus according to claim 4 and whereinat least one of said plurality of pressure-controlled drip irrigationemitter units includes a low pressure leakage prevention feature. 17.Drip irrigation apparatus according to claim 4 and wherein at least oneof said plurality of pressure-controlled drip irrigation emitter unitscomprises: an inlet aperture; a raised wall having a rim, said raisedwall and said rim surrounding said inlet aperture; and an elasticelement operative to be displaced when water pressure in said main waterflow channel exceeds a predetermined threshold, and to be in sealedengagement with said rim of said raised wall when water pressure in saidmain water flow channel does not exceed said predetermined threshold.18. Drip irrigation apparatus according to claim 4 and wherein at leastone of said plurality of pressure-controlled drip irrigation emitterunits comprises two mutually sealed portions.
 19. Drip irrigationapparatus according to claim 18 and wherein: a first one of said twomutually sealed portions comprises: a circumferential raised elongateportion; and an internal raised elongate portion extending between twosections of said at least one pressure-reducing pathway; and a secondone of said two mutually sealed portions comprises: a circumferentialelongate recess; and an internal elongate recess, said two mutuallysealed portions being sealed by engagement of said raised elongateportions with said elongate recesses.
 20. Drip irrigation apparatusaccording to claim 19 and wherein said raised elongate portions have agenerally triangular cross section, and said elongate recesses have agenerally rectangular cross section.
 21. Drip irrigation apparatusaccording to claim 19 and wherein said two mutually sealed portions aresealed ultrasonically.
 22. Drip irrigation apparatus according to claim21 and wherein said two mutually sealed portions are sealedultrasonically along said raised elongate portions and said elongaterecesses.
 23. Drip irrigation apparatus according to claim 22 andwherein at least one of said two mutually sealed portions and said atleast one pressure reducing pathway is not deformed by ultrasonicsealing of said raised elongate portions and said elongate recesses. 24.Drip irrigation apparatus according to claim 22 and wherein dimensionsof at least one of said two mutually sealed portions and said at leastone pressure reducing pathway are not changed by ultrasonic sealing ofsaid raised elongate portions and said elongate recesses.
 25. Dripirrigation apparatus according to claim 18 and wherein said at least onepressure reducing pathway maintains its functionality even when sealingbetween inwardly facing sides of said two mutually sealed portions isincomplete.
 26. Drip irrigation apparatus according to claim 19 andwherein said first one of said two mutually sealed portions includes acircumferential raised wall and an internal raised wall having aprotrusion therebetween, said protrusion being operative to at leastpartially prevent particular matter from flowing into said at least onepressure reducing pathway.
 27. Drip irrigation apparatus according toclaim 17 and wherein said raised wall comprises a non-circular wall, andsaid rim is configured such that at a predetermined threshold pressureacross said elastic element, said elastic element transitions fromgenerally complete circumferential disengagement with said rim togenerally complete circumferential engagement with said rim.
 28. Dripirrigation apparatus according to claim 27 and wherein said rim isconfigured such that at a second predetermined threshold pressure acrosssaid elastic element, said elastic element transitions from generallycomplete circumferential engagement with said rim to generally completecircumferential disengagement with said rim.
 29. Drip irrigationapparatus according to claim 27 and wherein said rim of saidnon-circular wall is non-planar.
 30. Drip irrigation apparatus accordingto claim 1 and wherein said main water flow channel is defined bywelding of one elongate edge of a sheet to an interior locationtherealong.
 31. Drip irrigation apparatus according to claim 30 andwherein said at least one secondary water flow channel is defined bywelding of another elongate edge of said sheet to a labyrinth definingstrip which is welded to said sheet at an exterior location therealong.32. Drip irrigation apparatus according to claim 1 and wherein said mainwater flow channel is defined by welding of first and second elongateedges of a first sheet at a seam location.
 33. Drip irrigation apparatusaccording to claim 32 and wherein said at least one secondary water flowchannel is defined by welding of a first elongate edge of a second sheetto said first elongate edge of said first sheet at said seam locationand by welding a second elongate edge of said second sheet to alabyrinth defining strip which is welded to said first sheet at anexterior location therealong.
 34. Drip irrigation apparatus according toclaim 1 and wherein said main water flow channel is defined by anelongate tube.
 35. Drip irrigation apparatus according to claim 34 andwherein said at least one secondary water flow channel is defined bywelding of a first elongate edge of a sheet to said elongate tube at afirst exterior location therealong and by welding of a second elongateedge of said sheet to a labyrinth defining strip which is welded to saidelongate tube at a second exterior location therealong.
 36. Dripirrigation apparatus according to claim 34 and wherein said at least onesecondary water flow channel is defined by welding of a first elongateedge of a sheet to said elongate tube at a first exterior locationtherealong and by welding of a second elongate edge of said sheet tosaid elongate tube at a second exterior location therealong, said sheethaving a labyrinth defining strip welded at a surface thereof whichfaces an exterior surface of said elongate tube.
 37. Drip irrigationapparatus according to claim 34 and wherein said at least one secondaryflow channel is defined by a second elongate tube surrounding saidelongate tube, said second elongate tube having welded at a firstlocation of an interior surface thereof a labyrinth defining strip andbeing welded at a second location of said interior surface thereof to anouter surface of said elongate tube.
 38. Drip irrigation apparatusaccording to claim 30 and wherein said main water flow channel haswelded at an interior location therealong at least one of said pluralityof pressure-controlled drip irrigation emitter unit.
 39. Drip irrigationapparatus according to claim 30 and wherein said at least one secondarywater flow channel includes material having at least one of weeping hosefunctionality and sweat irrigation functionality.
 40. Apressure-controlled drip irrigation emitter element comprising: a waterinlet; an inlet control chamber receiving water from said water inletvia an inlet aperture; a pressure reducing pathway receiving water fromsaid inlet control chamber; an outlet control chamber receiving waterfrom said pressure reducing pathway; an elastic element separating saidinlet control chamber and said outlet control chamber; and anon-circular wall surrounding said inlet aperture and having a rim, saidrim being configured such that at a predetermined threshold pressureacross said elastic element, said elastic element transitions fromgenerally complete circumferential disengagement with said rim togenerally complete circumferential engagement with said rim.
 41. Apressure-controlled drip irrigation emitter element comprising: a waterinlet; an inlet control chamber receiving water from said water inletvia an inlet aperture; a pressure reducing pathway receiving water fromsaid inlet control chamber; an outlet control chamber receiving waterfrom said pressure reducing pathway; and an elastic element separatingsaid inlet control chamber and said outlet control chamber, said inletcontrol chamber, said outlet control chamber and said pressure reducingpathway being defined by ultrasonic sealing of first and second emitterelement portions in a manner such that the dimensions of said pressurereducing pathway are not affected.
 42. A pressure-controlled dripirrigation emitter element according to claim 41 and wherein said inletaperture is surrounded by a non-circular wall having a rim, said rimbeing configured such that at a predetermined threshold pressure acrosssaid elastic element, said elastic element transitions from generallycomplete circumferential disengagement with said rim to generallycomplete circumferential engagement with said rim.
 43. Apressure-controlled drip irrigation emitter element according to claim40 and wherein said rim is configured such that at a secondpredetermined threshold pressure across said elastic element, saidelastic element transitions from generally complete circumferentialengagement with said rim to generally complete circumferentialdisengagement with said rim.
 44. A pressure-controlled drip irrigationemitter element according to claim 40 and wherein said rim of saidnon-circular wall is non-planar.
 45. A pressure-controlled dripirrigation emitter element according to claim 41 and wherein one of saidfirst and second emitter element portions includes a raised elongateportion and another of said first and second emitter element portionsincludes a corresponding elongate recess, said raised elongate portionand said elongate recess being ultrasonically welded together.
 46. Apressure-controlled drip irrigation emitter element according to claim45 and wherein said raised elongate portion has a generally triangularcross section and said elongate recess has a generally rectangular crosssection.
 47. A pressure-controlled drip irrigation emitter elementaccording to claim 45 and wherein said one of said first and secondemitter element portions also includes an internal raised elongateportion extending between two sections of said pressure-reducingpathway, and said another of said first and second emitter elementportions also includes a corresponding internal elongate recess, saidinternal raised elongate portion and said internal elongate recess beingultrasonically welded together.
 48. A pressure-controlled dripirrigation emitter element according to claim 47 and wherein saidinternal raised elongate portion has a generally triangular crosssection and said internal elongate recess has a generally rectangularcross section.
 49. A pressure-controlled drip irrigation emitter elementaccording to claim 41 and wherein said pressure reducing pathwaymaintains its functionality even when sealing between inwardly facingsides of said two mutually sealed portions is incomplete.
 50. Apressure-controlled drip irrigation emitter element according to claim41 and wherein one of said first and second emitter element portionsincludes a circumferential raised wall and an internal raised wallhaving a protrusion therebetween, said protrusion being operative to atleast partially prevent particular matter from flowing into saidpressure reducing pathway.
 51. A pressure-controlled drip irrigationemitter element disposed along an interior wall of a water supply tubecomprising: a water inlet coupled to said interior wall of said watersupply tube; an inlet control chamber receiving water from said waterinlet via an inlet aperture; a pressure reducing pathway receiving waterfrom said inlet control chamber, said pressure reducing pathway beingseparated from said interior wall of said water supply tube; an outletcontrol chamber receiving water from said pressure reducing pathway viaa pressure reducing pathway outlet passage; and an elastic elementseparating said inlet control chamber and said outlet control chamber,said pressure reducing pathway outlet passage extending from saidpressure reducing pathway, along a pathway extending between saidemitter element and said interior wall of said water supply tube, and tosaid outlet control chamber.
 52. A pressure-controlled drip irrigationemitter element according to claim 51 and wherein said inlet aperture issurrounded by a non-circular wall having a rim, said rim beingconfigured such that at a predetermined threshold pressure across saidelastic element, said elastic element transitions from generallycomplete circumferential disengagement with said rim to generallycomplete circumferential engagement with said rim.
 53. Apressure-controlled drip irrigation emitter element according to claim52 and wherein said rim is configured such that at a secondpredetermined threshold pressure across said elastic element, saidelastic element transitions from generally complete circumferentialengagement with said rim to generally complete circumferentialdisengagement with said rim.
 54. A pressure-controlled drip irrigationemitter element according to claim 52 and wherein said rim of saidnon-circular wall is non-planar.
 55. A pressure-controlled dripirrigation emitter element according to claim 51 and wherein said inletcontrol chamber, said outlet control chamber and said pressure reducingpathway are defined by ultrasonic sealing of first and second emitterelement portions in a manner such that the dimensions of said pressurereducing pathway are not affected.
 56. A pressure-controlled dripirrigation emitter element according to claim 55 and wherein one of saidfirst and second emitter element portions includes a raised elongateportion and another of said first and second emitter element portionsincludes a corresponding elongate recess, said raised elongate portionand said elongate recess being ultrasonically welded together.
 57. Apressure-controlled drip irrigation emitter element according to claim56 and wherein said raised elongate portion has a generally triangularcross section and said elongate recess has a generally rectangular crosssection.
 58. A pressure-controlled drip irrigation emitter elementaccording to claim 56 and wherein said one of said first and secondemitter element portions also includes an internal raised elongateportion extending between two sections of said pressure-reducingpathway, and said another of said first and second emitter elementportions also includes a corresponding internal elongate recess, saidinternal raised elongate portion and said internal elongate recess beingultrasonically welded together.
 59. A pressure-controlled dripirrigation emitter element according to claim 58 and wherein saidinternal raised elongate portion has a generally triangular crosssection and said internal elongate recess has a generally rectangularcross section.
 60. A pressure-controlled drip irrigation emitter elementaccording to claim 55 and wherein said pressure reducing pathwaymaintains its functionality even when sealing between inwardly facingsides of said two mutually sealed portions is incomplete.
 61. Apressure-controlled drip irrigation emitter element according to claim55 and wherein one of said first and second emitter element portionsincludes a circumferential raised wall and an internal raised wall,having a protrusion therebetween, said protrusion being operative to atleast partially prevent particular matter from flowing into saidpressure reducing pathway.